The electron impact spectra of butadiene and several substituted butadienes were measured and interpreted. Criteria were established to distinguish between Rydberg and valence transitions. A forbidden valence transition was observed around 7.4 eV in butadiene. The multiphoton ionization spectrum of butadiene was measured to the red of and inbetween the wavelengths previously investigated. Two optically inactive transitions were observed, one of which arises from a 4-photon resonance. A moderately fast pulsed value (speed approximately 0.2 msec FWHM) was developed as a supersonic nozzle source, tested, and found to work.